Thermoplastic modacrylic resin composition, method for manufacturing same, molded article of same, and acrylic fibers and method for manufacturing same

ABSTRACT

A thermoplastic modacrylic resin composition includes a modacrylic resin and a plasticizer. The modacrylic resin includes 15 to 85 wt % of acrylonitrile, 15 to 85 wt % of vinyl chloride and/or vinylidene chloride, and 0 to 20 wt % of another vinyl monomer, and the plasticizer is an organic compound that is compatible with the modacrylic resin and has a boiling point of at least 200° C. A method for manufacturing a thermoplastic modacrylic resin composition includes melt-kneading a powder mixture obtained by mixing a modacrylic resin powder and an organic compound that is compatible with the modacrylic resin and has a boiling point of at least 200° C. Acrylic fibers are composed of a thermoplastic modacrylic resin composition.

This application is a divisional filed pursuant to 35 U.S.C. § 121 ofU.S. patent application Ser. No. 15/717,284, filed Sep. 27, 2017, whichis a continuation of PCT/JP2016/059670, filed on Mar. 25, 2016. Thecontents of the priority applications are incorporated by reference intheir entirety.

TECHNICAL FIELD

One or more embodiments of the present invention relate to a meltprocessible thermoplastic modacrylic resin composition, a method formanufacturing the same, and a molded ankle of the same, as well asacrylic fibers and a method for manufacturing the same.

BACKGROUND

Conventionally, modacrylic fibers composed of a modacrylic resinobtained by copolymerizing acrylonitrile and a vinyl chloride monomerhave been used as flame-retardant materials or artificial hair whiletaking advantage of their characteristics of heat resistance and/orflame retardance. Since modacrylic resins have a decomposition startingtemperature that is lower than their softening temperature, they aredecomposed when being melt-processed. Usually, therefore, they arefiberized by a wet spinning method (Patent Documents 1 to 3). However,in the case of the wet spinning method, the drainage load is high andthe cost of solvent recovery is high. Therefore, Patent Document 4discusses melt spinning of modacrylic fibers.

PATENT DOCUMENTS

[Patent Document 1] JP6(1994)-287806A

[Patent Document 2] JP9(1997)-52907A

[Patent Document 3] JP2005-179876A

[Patent Document 4] JP2004-360090A

Patent Document 4 proposes to obtain a melt-spinnable composition byadding a (meth)acrylonitrile polymer as an agent for improvingprocessability to a polymer containing 17 to 86 wt % of halogen atomscomposed of 30 to 70 wt % of acrylonitrile and 70 to 30 wt % ofhalogen-containing vinyl monomers. However, a large amount of aplasticizer is required in the production of the composition of PatentDocument 4. This largely deteriorates appearance, heat resistance, andspinning stability because conventional plasticizers lack compatibilitywith resin.

One or more embodiments of the present invention provide, by utilizing aparticular plasticizer, a modacrylic resin composition with good meltprocessability, a method for manufacturing the same, and a moldedarticle of the same, as well as acrylic fibers and a method formanufacturing the same.

SUMMARY

One or more embodiments of the present invention relate to athermoplastic modacrylic resin composition including a modacrylic resinand a plasticizer, the modacrylic resin containing 15 to 85 wt % ofacrylonitrile, 15 to 85 wt %) of vinyl chloride and/or vinylidenechloride, and 0 to 20 wt % of other vinyl monomers, and the plasticizerbeing an organic compound that is compatible with the modacrylic resinand has a boiling point of at least 200° C.

In one or more embodiments of the present invention, the thermoplasticmodacrylic resin composition further may include a stabilizer, thestabilizer being at least one selected from the group consisting of anepoxy-based heat stabilizer, a hydrotalcite-based heat stabilizer, analiphatic acid anhydride, and an alicyclic acid anhydride. Thestabilizer may be at least one selected from the group consisting ofpoly(glycidyl methacrylate), tetrabromobisphenol A diglycidyl ether,hydrotalcite, a dodecenylsuccinic anhydride, and a hexahydrophthalicanhydride.

According to one or more embodiments of the present invention, withrespect to 100 parts by weight of the modacrylic resin, thethermoplastic modacrylic resin composition may contain 0.1 to 50 partsby weight of the organic compound that is compatible with the modacrylicresin and has a boiling point of at least 200° C. In yet anotherembodiment, with respect to 100 parts by weight of the modacrylic resin,the thermoplastic modacrylic resin composition may contain 0.1 to 30parts by weight of at least one of stabilizer selected from the groupconsisting of an epoxy-based heat stabilizer, a hydrotalcite-based heatstabilizer, an aliphatic acid anhydride, and an alicyclic acidanhydride.

In one or more embodiments of the present invention, the organiccompound that is compatible with the modacrylic resin and has a boilingpoint of at least 200° C. is at least one selected from the groupconsisting of dimethyl sulfone, diethyl sulfone, dipropyl sulfone,dibutyl sulfone, diphenyl sulfone, vinyl sulfone, ethyl methyl sulfone,methyl phenyl sulfone, methyl vinyl sulfone, 3-methylsulfolane, dipropylsulfoxide, tetramethylene sulfoxide, diisopropyl sulfoxide, methylphenyl sulfoxide, dibutyl sulfoxide, diisobutyl sulfoxide, sulfoxide,diphenyl sulfoxide, benzyl sulfoxide, lactide lactate, pyrrolidone,ε-caprolactam, N-methylcaprolactam, γ-butyrolactone, γ-hexalactone,γ-heptalactone, γ-octalactone, ε-caprolactone, and ε-octalactone. In oneor more embodiments of the present invention, the organic compound thatis compatible with the modacrylic resin and has a boiling point of atleast 200° C. has a melting point of at least 60° C. The organiccompound that is compatible with the modacrylic resin and has a boilingpoint of at least 200° C. may be at least one selected from the groupconsisting of dimethyl sulfone and lactide lactate.

In one or more embodiments of the present invention, the thermoplasticmodacrylic resin composition may be in a molten state. In yet anotherembodiment, in the thermoplastic modacrylic resin composition, theaverage transmittance for visible light in the wavelength range of 427to 675 nm may be at least 25%.

Furthermore, one or more embodiments of the present invention relate toa method for manufacturing the thermoplastic modacrylic resincomposition, the method including melt-kneading a powder mixtureobtained by mixing a modacrylic resin powder and a plasticizer togetherto obtain a thermoplastic modacrylic resin composition, with themodacrylic resin powder being obtained by polymerizing a total of 100parts by weight of a vinyl monomer mixture containing 15 to 85 parts byweight of acrylonitrile, 15 to 85 parts by weight of vinyl chlorideand/or vinylidene chloride, and 0 to 20 parts by weight of other vinylmonomers, and the plasticizer being an organic compound that iscompatible with the modacrylic resin and has a boiling point of at least200° C.

Moreover, one or more embodiments of the present invention relate to amolded article of a thermoplastic modacrylic resin composition, themolded article being composed of the thermoplastic modacrylic resincomposition and having a predetermined shape.

According to one or more embodiments of the present invention, themolded article of the thermoplastic modacrylic resin composition may beone selected from the group consisting of a film, a plate, fibers, anextrusion molded article, and an injection molded article.

Furthermore, one or more embodiments of the present invention relate toacrylic fibers, the acrylic fibers being composed of the thermoplasticmodacrylic resin composition.

Moreover, one or more embodiments of the present invention relate to amethod for manufacturing acrylic fibers, the method includingmelt-spinning the thermoplastic modacrylic resin composition to obtainacrylic fibers.

One or more embodiments of the present invention can provide athermoplastic modacrylic resin composition with good meltprocessability, a method for manufacturing the same, and a moldedarticle of the same. Furthermore, one or more embodiments of the presentinvention allow acrylic fibers to be manufactured by melt spinning andthus can provide acrylic fibers manufactured by melt spinning.

BRIEF DESCRIPTION OF THE DRAWINGS

The FIGURE is a laser micrograph (×1000) of the cross-sections of theacrylic fibers obtained in Example 12.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The inventors of the present disclosure have found that when an organiccompound that has a boiling point of at least 200° C. and is compatiblewith a modacrylic resin containing 15 to 85 wt % of acrylonitrile, 15 to85 wt % of vinyl chloride and/or vinylidene chloride, and 0 to 20 wt %of other vinyl monomers is used as a plasticizer, a thermoplasticmodacrylic resin composition with improved melt processability isobtained.

In one or more embodiments of the present invention, the modacrylicresin and the plasticizer are compatible with each other. In one or moreembodiments of the present invention, the term “compatible” denotes thatthe modacrylic resin is melted when 10 mg of modacrylic resin and 2 g ofa plasticizer candidate substance are placed in a 19-mL glass tube madeof borosilicate glass and a silicon plug is fitted into the glass tube,which then is heated at 160° C. for 30 minutes while being stirred fromtime to time. Furthermore, in one or more embodiments of the presentinvention, the term “boiling point” denotes the normal boiling pointunder the condition of 1 atmospheric pressure (760 mmHg).

In terms of excellent sense of touch, the modacrylic resin may contain15 to 85 wt % of acrylonitrile, 15 to 85 wt % of vinyl chloride, and 0to 20 wt % of other vinyl monomers.

In terms of improving heat resistance, the modacrylic resin may containacrylonitrile in an amount of at least 20 wt %, or at least 25 wt %, orat least 30 wt % In terms of improving flame retardance, the modacrylicresin may contain vinyl chloride and/or vinylidene chloride in an amountof at least 20 wt %, or at least 25 wt %, or at least 30 wt %. In termsof achieving a good balance between heat resistance and flameretardance, the modacrylic resin may contain acrylonitrile in an amountof not more than 80 wt %, or not more than 75 wt %, or not more than 70wt %. Moreover, the modacrylic resin may contain vinyl chloride and/orvinylidene chloride in an amount of not more than 80 wt %, or not morethan 75 wt %, or not more than 70 wt %. In terms of balancingprocessability, heat resistance, flame retardance, colorability, anddyeability, the modacrylic resin may contain other vinyl monomers in anamount of 0.1 to 1.5 wt %, or 0.1 to 10 wt %.

The modacrylic resin is one obtained by copolymerizing a total of 100parts by weight of a vinyl monomer mixture containing 15 to 85 parts byweight of acrylonitrile, 15 to 85 parts by weight of vinyl chlorideand/or vinylidene chloride, and 0 to 20 parts by weight of other vinylmonomers.

In terms of excellent sense of touch, the modacrylic resin may be oneobtained by copolymerizing a total of 100 parts by weight of a vinylmonomer mixture containing 15 to 85 parts by weight of acrylonitrile, 15to 85 parts by weight of vinyl chloride, and 0 to 20 parts by weight ofother vinyl monomers.

In terms of improving heat resistance, the vinyl monomer mixture maycontain acrylonitrile in an amount of at least 20 parts by weight, or atleast 25 parts by weight, or at least 30 parts by weight, with the totalweight of the vinyl monomer mixture being taken as 100 parts by weight.In terms of improving flame retardance, the vinyl monomer mixture maycontain vinyl chloride and/or vinylidene chloride in an amount of atleast 20 parts by weight, or at least 25 parts by weight, or at least 30parts by weight, with the total weight of the vinyl monomer mixturebeing taken as 100 parts by weight. In terms of achieving a good balancebetween heat resistance and flame retardance, the vinyl monomer mixturemay contain acrylonitrile in an amount of not more than 80 parts byweight, or not more than 75 parts by weight, or not more than 70 partsby weight, with the total weight of the vinyl monomer mixture beingtaken as 100 parts by weight. Furthermore, the vinyl monomer mixture maycontain vinyl chloride and/or vinylidene chloride in an amount of notmore than 80 parts by weight, or not more than 75 parts by weight, ornot more than 70 parts by weight, with the total weight of the vinylmonomer mixture being taken as 100 parts by weight. In terms ofbalancing processability, heat resistance, flame retardance,colorability, and dyeability, the vinyl monomer mixture may containother vinyl monomers in an amount of 0.1 to 15 parts by weight, or 0.1to 10 parts by weight, with the total weight of the vinyl monomermixture being taken as 100 parts by weight.

Other vinyl monomers are not particularly limited as long as they arevinyl monomers other than acrylonitrile, vinyl chloride, and vinylidenechloride. Other vinyl monomers may be used individually or incombination of two or more thereof.

In terms of increasing adsorption to pigments, other vinyl monomers tobe used may be acid functional group-containing vinyl monomers. Examplesof the acid functional group-containing vinyl monomers includecarboxylic acid-based monomers and sulfuric acid-based monomers.Examples of carboxylic acid-based monomers include carboxylic acid (suchas acrylic acid or methacrylic acid) group-containing vinyl monomers andsalts thereof. Examples of sulfuric acid based monomers include vinylmonomers containing a sulfuric acid group such as a vinyl sulfuric acid,styrenesulfonic acid, allyl sulfonic acid, methallylsulfonic acid,2-acrylamido-2-methylpropanesulfonic acid, or isoprenesulfonic acidgroup, and salts thereof.

Furthermore, in terms of improving the processability by reducing theprocess temperature achieved by reducing the glass transitiontemperature of the modacrylic resin and suppressing coloration causedthereby, other vinyl monomers to be used may be, for example, alkyl(meth)acrylate, 1-vinyl esters, styrene, and derivatives thereof.Examples of alkyl (meth)acrylate include methyl (meth)acrylate, ethyl(meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate,2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl(meth)acrylate, and oleyl (meth)acrylate. Examples of 1-vinyl estersinclude vinyl formate and vinyl acetate. Examples of styrene-based vinylmonomers include styrene, α-methylstyrene, and styrene derivatives suchas indene. In one or more embodiments of the present invention,(meth)acrylate denotes acrylate and/or methacrylate.

Furthermore, in terms of improving heat resistance by increasing theglass transition temperature of the modacrylic resin, other vinylmonomers to be used may be vinyl halides such as vinyl bromide,1,1-dibromoethene, vinyl iodide, and 1,1-diiodoethene other than vinylchloride and vinylidene chloride.

Moreover, in terms of providing the modacrylic resin withwater-repellent and oil-repellent functions, other vinyl monomers to beused may be vinyl fluorides such as vinyl fluoride and1,1-difluoroethene.

The above-mentioned modacrylic resin can be obtained by radicalpolymerization of acrylonitrile vinyl chloride and/or vinylidenechloride, and other vinyl monomers. The polymerization method is notparticularly limited and can be carried out by, for example, suspensionpolymerization or solution polymerization. In one or more embodiments ofthe present invention, the polymerization method may be aqueoussuspension polymerization since polymer particles can be separated andwashed easily after polymerization. The suspension polymerization is notparticularly limited and can be carried out by a known common method.

For the radical polymerization, for example, a thiol group-containingcompound such as 2-mercaptoethanol, 2-mercaptoethylamine, thioglycollicacid, mercaptopropionic acid, thioglycerol, 3-mercapto-1,2-propanediol,or dodecyl mercaptan or α-methylstyrene dimer may be used as a chaintransfer agent. Furthermore, for example, a dithiobenzoate-basedcompound, a trithiocarbonate-based compound, a dithiocarbamate-basedcompound, or a xanthate-based compound can also be used as a reversibleaddition-fragmentation chain transfer agent.

The organic compound that is compatible with the modacrylic resin andhas a boiling point of at least 200° C. (hereinafter, also referred tosimply as a “plasticizer for modacrylic resin”) is not particularlylimited as long as it is an organic compound that is compatible with themodacrylic resin and has a boiling point of at least 20° C. Examples ofthe plasticizer for modacrylic resin that can be used includesulfone-based compounds such as dimethyl sulfone, diethyl sulfone,dipropyl sulfone, dibutyl sulfone, diphenyl sulfone, vinyl sulfone,ethyl methyl sulfone, methyl phenyl sulfone, methyl vinyl sulfone, and3-methylsulfolane; sulfoxide-based compounds such as dipropyl sulfoxide,tetramethylene sulfoxide, diisopropyl sulfoxide, methyl phenylsulfoxide, dibutyl sulfoxide, diisobutyl sulfoxide, di-p-tolylsulfoxide, diphenyl sulfoxide, and benzyl sulfoxide lactides such aslactide lactate; lactams such as pyrrolidone, ε-caprolactam, andN-methylcaprolactam; and lactones such as γ-butyrolactone,γ-hexalactone, γ-heptalactone, γ-octalactone, ε-caprolactone, andε-octalactone. Furthermore, the plasticizers for modacrylic resin may beused individually or in combination of two or more thereof.

When fibers are maintained at a higher temperature than their meltingpoint, the plasticizer for modacrylic resin may become liquid to leachout to fiber surfaces, which results in a deterioration in theappearance and sense of touch of the fibers. Specifically, when thetemperature returns to room temperature (25±5° C.) afterwards, theplasticizer tends to become solid and thereby the fibers adhere to oneanother. For example, since the room temperature in an inboard containermay increase up to 60° C. during overseas transportation and thetemperature also increases to 90° C. during the fiber processing,although for a short time, the melting point of the plasticizer formodacrylic resin may be at least 60° C., or at least 90° C. It ispossible to use, for example, dimethyl sulfone, lactide lactate, orε-caprolactam.

The thermoplastic modacrylic resin composition may contain the organiccompound that is compatible with the modacrylic resin and has a boilingpoint of at least 200° C. in an amount of 0.1 to 50 parts by weight, or0.5 to 30 parts by weight, or 1 to 20 parts by weight, with respect to100 parts by weight of the modacrylic resin. For example, in the casewhere dimethyl sulfone is used, 5 parts by weight or more thereofresults in good melt processability, and when 20 parts by weight ofdimethyl sulfone is mixed together, the melt process can be carried outat a lower temperature, for example, even at 115° C. that is higher thanthe melting point of dimethyl sulfone by 5° C. In the case of 50 partsby weight or less, good melt processability is obtained, and the resinviscosity in melt-kneading increases and thereby kneading efficiencytends to improve.

The thermoplastic modacrylic resin composition may further contain astabilizer to have thermal stability. The stabilizer is not particularlylimited as long as it provides thermal stability in terms of suppressingcoloration in brown or red while improving melt processability, thestabilizer may be at least one of stabilizer (hereinafter, also referredto simply as a “stabilizer for modacrylic resin”) selected from thegroup consisting of an epoxy-based heat stabilizer, a hydrotalcite-basedheat stabilizer, an aliphatic acid anhydride, and an alicyclic acidanhydride, such as an epoxy-based heat stabilizer and/or ahydrotalcite-based heat stabilizer. Furthermore, in terms of improving,transparency, the stabilizer for modacrylic resin may be an epoxy-basedheat stabilizer and/or a hydrotalcite-based heat stabilizer that have aboiling point of at least 200° C.

Examples of the epoxy-based heat stabilizer that can be used include ahomopolymer or copolymer of at least one of vinyl monomers selected fromthe group consisting of butyl glycidyl ether, neopentyl glycoldiglycidyl ether phenyl glycidyl ether, o-cresyl glycidyl ether,m-/p-cresyl glycidyl ether, glycidyl methacrylate, 1,6-hexanedioldiglycidyl ether, trimethylolpropane polyglycidyl ether, diglycidylhexahydrophthalate, hydrogenated bisphenol-A glycidyl ether, propyleneglycol diglycidyl ether, tripropylene glycol diglycidyl ether,polypropylene glycol diglycidyl ether, fatty acid-modified epoxy,diethylene glycol diglycidyl ether, polyethylene glycol diglycidylether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether,polyglycerol polyglycidyl ether, sorbitol-based polyglycidyl ether,1,3,5-tris(2,3-epoxypropyl)-1,3,5-triazine, tetrahydrophthalic aciddiglycidyl ester, and glycidyl acrylate. In terms of colorationsuppression and transparency, it is possible to use, for example,poly(glycidyl methacrylate), a copolymer of glycidyl methacrylate,tetrabromobisphenol A diglycidyl ether, diglycidyl hexahydrophthalate,or hydrogenated bisphenol-A glycidyl ether. For example, poly(glycidylmethacrylate), a copolymer of glycidyl methacrylate, ortetrabromobisphenol A diglycidyl ether may be used, which has a boilingpoint of at least 200° C. and is in a solid form at 50° C.

The hydrotalcite-based heat stabilizer is not particularly limited aslong as it is a hydrotalcite compound. It may be a natural product ormay be a synthetic product. For example, ALCAMIZER (registered tradename) manufactured by Kyowa Chemical Industry Co., Ltd. can be used.

The aliphatic acid anhydride is not particularly limited as long as itdoes not volatilize during melt processing and has a heat stabilizingeffect. For example, an alkenyl succinic anhydride such as adodecenylsuccinic anhydride (a 2-dodecen-1-ylsuccinic anhydride), a2-octen-1-ylsuccinic anhydride, or a 2-hexadecen-1-ylsuccinic anhydridecan be used. Specifically, for example, “RIKACID OSA” or “RIKACID DDSA”(product names) manufactured by New Japan Chemical Co., Ltd. or“PDSA-DA” manufactured by Sanyo Chemical industries, Ltd. can be used.

The alicyclic acid anhydride is not particularly limited as long as ithas a heat stabilizing effect. For example, a hexahydrophthalicanhydride, a methylhexahydrophthalic anhydride, amethyltetrahydrophthalic anhydride, or amethyl-3,6-endomethylene-1,2,3,6-tetrahydrophthalic anhydride cart beused. Specifically, for example, “RIKACID HH,” “RIKACID MH,” or “RIKACIDMH-700G” (product names) manufactured by New Japan Chemical Co., Ltd. or“HN-2200,” “HN-2000,” “HN-5500,” or “MHAC-P” manufactured by HitachiChemical Co., Ltd. can be used.

The thermoplastic modacrylic resin composition may contain at least oneof stabilizer selected from the group consisting of an epoxy-based heatstabilizer, a hydrotalcite-based heat stabilizer, an aliphatic acidanhydride, and an alicyclic acid anhydride in an amount of 0.1 to 30parts by weight, or 0.2 to 20 parts by weight, or 0.5 to 10 parts byweight, with respect to 100 parts by weight of the modacrylic resin. Inthe case of at least 0.1 part by weight, a high coloration suppressingeffect is obtained. Furthermore, in the case of 30 parts by weight orless, a high coloration suppressing effect is obtained and transparencycan be ensured and furthermore, degradation in mechanical properties ofa modacrylic resin molded body is minimal.

The thermoplastic modacrylic resin composition may contain otherstabilizers in addition to the above-mentioned stabilizer for modacrylicresin as required. These other stabilizers are other than the stabilizerfor modacrylic resin and are not limited as long as they have thermalstability and/or a coloration suppressing effect. For example, metalsoap, organic phosphite, and tin stabilizers can be used. These otherstabilizers may be used individually or in combination of two or morethereof. The amount of other stabilizers to be added is not limited aslong as it is not more than 10 parts by weight with respect to 100 partsby weight of the modacrylic resin.

The thermoplastic modacrylic resin composition may contain a lubricant,within a range where one or more embodiments of the present inventionare not impaired, in terms of reducing the heat generation caused by thefriction and shear between the modacrylic resin and a processing machineand improving fluidity and mold releasability Examples of the lubricantthat can be used include fatty acid ester-based lubricants such asstearic acid monoglyceride, stearyl stearate, hydrocarbon-basedlubricants such as liquid paraffin, paraffin wax, and syntheticpolyethylene wax, fatty acid-based lubricants such as stearic acid,higher alcohol-based lubricants such as stearyl alcohol, aliphaticamide-based lubricants such as stearic acid amide, oleic acid amide, anderucic acid amide, alkylene fatty acid amide-based lubricants such asmethylene bis stearic acid amide and ethylene bis stearic acid amide, aswell as metal soap-based lubricants such as lead stearate, zincstearate, calcium stearate, and magnesium stearate. These may be usedindividually or in combination of two or more thereof. The amount oflubricant to be added is not limited as long as it is not more than 10parts by weight with respect to 100 parts by weight of the modacrylicresin.

The thermoplastic modacrylic resin composition may contain a processingaid such as an acrylic-based processing aid, within a range where one ormore embodiments of the present invention are not impaired. When fibersare composed of the thermoplastic modacrylic resin composition, a(meth)acrylate-based polymer and/or a styrene-acrylonitrile copolymermay be contained as a processing aid in terms of improving spinnability.Examples of the (meth)acrylate-based polymer that can be used includecopolymers of (meth)acylate with a copolymer component such as butyl(meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate,styrene, vinyl acetate, or acrylonitrile. Furthermore, examples of the(meth)acylate-based polymer that can be used include those commerciallyavailable, for example, “Kane Ace PA20” and “Kane Ace PA101”manufactured by Kaneka Corporation. The amount of processing aid to beadded is not limited as long as it is not more than 3 parts by weightwith respect to 100 parts by weight of the modacrylic resin.

The thermoplastic modacrylic resin composition is used in a moltenstate, that is, it can be used as a molten material. The molten materialcan be obtained by melt-kneading the thermoplastic modacrylic resincomposition. The method of melt-kneading is not particularly limited anda general method of melt-kneading a thermoplastic resin composition canbe used.

In terms of convenience of operation, first, the plasticizer formodacrylic resin is mixed with the modacrylic resin powder and thereby apowder mixture is obtained. In terms of easiness in mixing, themodacrylic resin powder may have a moisture content of not more than 2mass %, or not more than 0.5 mass %. The moisture content of themodacrylic resin can be measured under the conditions of 160° C. and 10minutes using a heating and drying method moisture analyzer MXmanufactured by A&D Company, Limited. In one or more embodiments of thepresent invention the stabilizer for modacrylic resin may be mixed in.Furthermore, for example, other stabilizers, lubricants, and processingaids are mixed in as required. In one or more embodiments of the presentinvention, the term “powder” denotes that the mean particle size is atleast 1 μm. Moreover, the mean particle size denotes D50 (a median size)measured with a Laser Scattering Particle Size Distribution Analyzer“Partica LA-950V2” manufactured by HORIBA, Ltd. For the above-mentionedmixing, for example, a mixer such as a Henschel mixer, a super mixer, ora ribbon blender can be used, although not particularly limited thereto.The conditions such as temperature and time for the mixing operation arenot particularly limited as long as a powder mixture can be obtained. Interms of convenience of mixing operation, the modacrylic resin powdermay have a mean particle size of 10 to 500 μm, or 50 to 250 μm. In termsof easiness in obtaining a powder mixture and in terms of allowingmelt-adsorption of various additives on the surface of the modacrylicresin powder as required, the temperature may be set in the range of 0to 120° C. during the mixing operation and is reduced to a temperaturethat is lower than the glass transition temperature of the powdermixture by at least 10° C. at the end of the mixing operation so as toprevent the powder from fusing together or to equipment such as pipingduring its transfer.

Next, the powder mixture is melt-kneaded. The temperature used duringthe melt-kneading is at least the glass transition temperature of akneaded mixture of the modacrylic resin and the plasticizer formodacrylic resin, and in terms of suppressing coloration that is causedby thermal decomposition of the modacrylic resin, the temperature may be40 to 200° C. or 80 to 185° C., or 120 to 175° C., or 120 to 170° C. Forkneading, for example, a kneader such as a single screw extruder a twinscrew extruder, or a plastomill can be used, although not particularlylimited thereto. In one or more embodiments of the present invention,the extruder may be operated at a temperature of, for example, 120 to175° C.

According to various embodiments of the present invention, thethermoplastic modacrylic resin composition is transparent in a moltenstate in terms of improving the rate of expression of natural color toneof dyes or pigments when used for an application that requires toning.For example, the average transmittance for visible light in thewavelength range of 427 to 675 nm may be at least 25%, or at least 35%,or at least 40%. In one or more embodiments of the present invention,the term “transmittance” denotes one obtained by measuring thetransmittance of a resin plate produced by hot-pressing thethermoplastic modacrylic resin composition in a molten state into a 1-mmthick plate. Furthermore, in one or more embodiments of the presentinvention the average transmittance for visible light in the wavelengthrange of 427 to 675 nm denotes the average between the transmittance ata wavelength of 476.59 nm and the transmittance at a wavelength of625.31 nm.

The thermoplastic modacrylic resin composition is processed into apredetermined shape and thereby a molded article can be obtained. Themolding method is not particularly limited and examples thereof includean extrusion molding method, an injection molding method, an insertmolding method, a sandwich molding method, a foam molding method, apress molding method, a blow molding method, a calendar molding method,a rotational molding method, a slush molding method, a dip moldingmethod, and a cast molding method. Examples of the molded articleinclude a film, a plate, fibers, an extrusion molded article, and aninjection molded article. The molded article may be a foamed article andmay be porous. In the present invention, the term “film” denotes onethat is flexible and is in a faun of a thin film with a thickness of notmore than 200 μm, while the term “plate” denotes one that is notflexible and is in a form of a thin film or a plate with a thickness ofat least 200 μm.

The molded article can be used suitably for applications that requireflame retardance or heat resistance. The molded article can be used for,for example, automobiles, household electric appliances, industrialparts, civil engineering and construction, commodities, packagingmaterials, and artificial leather. Specifically, examples of theapplications for vehicles such as automobiles include vehicle exteriorparts, vehicle interior parts, instrument panels, consoles, door sheets,ceilings, under carpets, and trunk sheets. Examples of the applicationsfor household electric appliances include wire coating, housings andparts for electronics products, and housings and parts for whitehousehold electric appliances. Examples of the applications forindustrial pans include pipes, tubes, gaskets, parts for machinery andappliances, hot melt adhesives, heat insulating materials, and pipeprotection materials. Examples of the applications for civil engineeringand construction include pipes, flat plates, construction curing sheets,window frames, screen doors, sidings, decks, flooring materials,wallpapers, tile carpets, and cushion floors. Examples of generalapplications and the applications for commodities include shoe soles,gloves, tapes, adhesive tapes, various bottles, dolls, artificial hairs,and fabrics. Examples of the applications for packaging materialsinclude containers, packing materials, and buffer materials. Examples ofthe applications for artificial leather include wallpapers, vehicle seatsheets, furniture, bags, footwear, pouches, clothing, mats, and carpets.

Acrylic fibers can be composed of the thermoplastic modacrylic resincomposition. Specifically, the thermoplastic modacrylic resincomposition is melt-spun and thereby acrylic fibers can be obtained,First, the thermoplastic modacrylic resin composition is melt-spun intofibrous undrawn yarns. Specifically, a melt-kneaded mixture of thethermoplastic modacrylic resin composition melt-kneaded with anextruder, for example, a single screw extruder, a counter-rotating twinscrew extruder, or a conical twin screw extruder, is discharged from aspinning nozzle by the extruder and then is passed through a heatingcylinder to be increased in temperature up to at least a temperaturethat allows a fiberized product of the thermoplastic modacrylic resincomposition to be taken off by a take-off machine, and thereafter it istaken up while being cooled to a temperature equal to or lower than theglass transition point by a method such as air cooling or forced-aircooling, thus forming undrawn yarns. In one or more embodiments of thepresent invention, the extruder may be operated in the temperature rangeof, for example, 120 to 220° C. The ratio of the take-up speed to thedischarge speed is not particularly limited, but the fiberized productmay be taken up at a speed ratio in the range of, for example, 1 to 100times. The diameter of the spinning nozzle is not particularly limitedbut may be, for example, 0.05 to 2 mm, or 0.1 to 1 mm. In one or moreembodiments of the invention, extrusion may be carried out at atemperature equal to or higher than the temperature that prevents amaterial discharged from the spinning nozzle from exhibiting meltfracture. The temperature of the spinning nozzle may be at least 160°C., or at least 170° C. The temperature of the heating cylinder may beat least 250° C., or at least 280° C. The cooling temperature may be−196 to 40° C., or 0 to 30° C. by air cooling and may be 5 to 6° C., or10 to 40° C. by water cooling.

The undrawn yarns obtained above can be subjected to a drawing treatmentand a thermal relaxation treatment by known methods. For example, whenused as artificial hair, they may be produced as fibers having a singlefiber fineness of 2 to 100 dtex. With respect to the conditions for thedrawing treatment, the draw ratio may be set to be around 1.1 to 6times, or around 2 to 4.5 times, in a thy heat atmosphere with a drawingtreatment temperature of 70 to 150° C. The fibers that have beensubjected to the drawing treatment may be subjected to a thermalrelaxation treatment to be relaxed at a relaxation rate of 1 to 50%, orat a relaxation rate of 2 to 40%, and thereby the thermal shrinkage ratecan be reduced. Furthermore, in order also to smoothen the unevenness ofthe fiber surfaces to obtain a smooth texture similar to that of humanhair, the thermal relaxation treatment may be used. Moreover, it is alsopossible to wash undrawn yarns or drawn yarns with water to control thefineness. In one or more embodiments of the present invention, thesingle fiber fineness may be measured according to JIS L 1013.

EXAMPLES

One or more embodiments of the present invention are described infurther details using the following examples. However, the presentinvention is not limited to the following examples. In the following,unless otherwise indicated, the term “part(s)” denotes part(s) by weightand “%” denotes wt %.

Synthesis Example 1

With respect to 40.4 parts by weight of acrylonitrile and 59.1 parts byweight of vinyl chloride, 270 parts by weight of ion exchanged water wasused, and 0.1 part by weight of ammonium persulphate, 0.09 part byweight of sodium sulfite, and 0.07 part by weight of sulfuric acid (62.5to 63.5 wt %) as polymerization initiators as well as 0.8 part by weightof sodium lauryl sulfate as a surfactant were used. With the pH in thepolymerization system being adjusted to 2.3, emulsion polymerization wascarried out at a polymerization temperature of 39° C. for apolymerization time of 7 hours. Thus, a modacrylic resin latex wasobtained. During the polymerization, 0.5 part by weight of sodiumstyrenesulfonate was continuously added to the polymerization system inan equal amount from two hours to six hours after the initiation of thepolymerization. Furthermore, 29.6 parts by weight of 40.4 parts byweight of acrylonitrile used herein was continuously added to thepolymerization system in an equal amount from immediately after theinitiation of the polymerization to 6.5 hours thereafter aspolymerization progresses. Furthermore, in order to keep thepolymerization rate constant, a part (0.09 part by weight) of theammonium persulphate used herein was continuously added. The polymerthus obtained was composed of 49.4 wt %) of acrylonitrile, 50.0 wt %) ofvinyl chloride, and 0.6 wt % of sodium styrenesulfonate. After that,salting-out, dehydration, water washing, dehydration, and dryingtreatments were carried out by common methods and thereby a modacrylicresin powder (with a mean particle size of 70 μm and a moisture contentof 0.3 mass %) was obtained. The mean particle size of the modacrylicresin is D50 measured using a Laser Scattering Particle SizeDistribution Analyzer “Partica LA-950V2” manufactured by HORIBA Ltd. Themoisture content of the modacrylic resin was measured under theconditions of 160° C. and 10 minutes using a heating and drying methodmoisture analyzer MX manufactured by A&D Company, Limited.

Evaluation Examples 1 to 20

10 mg of the modacrylic resin obtained in Synthesis Example 1 was placedin a 19-mL glass tube made of borosilicate glass, and 2.0 g of acompound indicated in Table 1 below was added thereto. Thereafter, asilicon plug was inserted into the glass tube. Then an operation, inwhich it was immersed in an oil bath set at 160° C. was taken out of theoil bath every five minutes, was stirred with a vortex mixer for fiveseconds, and then was put back into the oil bath, was repeated sixtimes, and thus it was heated at 160° C. for a total of 30 minutes.After 30 minutes, it was visually checked whether the modacrylic resinwas dissolved uniformly in the compound. The results are shown in Table1 below

TABLE 1 Solubility of Modacrylic Compound Resin Evaluation Ex. 1Dimethyl sulfone Dissolved Evaluation Ex. 2 Lactide lactate DissolvedEvaluation Ex. 3 ε-Caprolactam Dissolved Evaluation Ex. 4γ-Butyrolactone Dissolved Evaluation Ex. 5 ε-Caprolactone DissolvedEvaluation Ex. 6 Dimethyl sulfoxide Dissolved Evaluation Ex. 7N,N-Dimethylformamide Dissolved Evaluation Ex. 8 N,N-DimethylacetamideDissolved Evaluation Ex. 9 Epoxidized soybean oil Undissolved(manufactured by DIC, W-100-EL) Evaluation Ex. 10 Bis(2-ethylhexyl)phthalate Undissolved Evaluation Ex. 11 Tris(2-ethylhexyl) trimellitateUndissolved Evaluation Ex. 12 Bis(2-ethylhexyl) adipate UndissolvedEvaluation Ex. 13 Stearic acid Undissolved Evaluation Ex. 14 Methylstearate Undissolved Evaluation Ex. 15 Polyester adipate Undissolved(manufactured by ADEKA, W-230-H)

Example 1

To 100 parts by weight of the modacrylic resin powder obtained inSynthesis Example 1, 20 parts by weight of dimethyl sulfone as aplasticizer, 10 parts by weight of poly(glycidyl methacrylate)(manufactured by NOF Corporation, product name “Marproof (registeredtrade name) G01100”) as a stabilizer, as well as 0.5 part by weight of(meth)acrylate-based polymer (manufactured by Kaneka Corporation,product name “Kane Ace PA20”), 0.5 part by weight of calcium stearate,1.2 parts by weight of magnesium stearate, 0.8 part by weight ofsynthetic polyethylene wax, and 0.7 part by weight of stearic acid(manufactured by NOF Corporation, product name “Stearic Acid Sakura”) asother additives were added, which then was increased in temperature to110° C. while being mixed together using a Henschel mixer. Thereafter,it was cooled down to 50° C. and thereby a powder mixture was obtained.Subsequently, 62 g of the powder mixture was kneaded with a LaboPlastomill (manufactured by Toyo Seiki Seisaku-sho, Ltd., model number“4C150”) under the conditions of 145° C., 50 rpm, and 4.5 minutes andthus a melt-kneaded mixture was obtained.

Example 2

A melt-kneaded mixture was obtained in the same manner as in Example 1except that 10 parts of hydrotalcite (manufactured by Kyowa ChemicalIndustry Co., Ltd., product name “ALCAMIZER (registered trade name) 1”)was used instead of 10 parts of poly(glycidyl methacrylate).

Example 3

A melt-kneaded mixture was obtained in the same manner as in Example 2except that melt-kneading was carried out under the conditions of 115°C. and 20 rpm for two minutes and then was further carried out under theconditions of 115° C. and 50 rpm for 4.5 minutes.

Example 4

A melt-kneaded mixture was obtained in the same manner as in Example 1except that 10 parts of tetrabromobisphenol A diglycidyl ether(manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., product name“SR-BSP”) was used instead of 10 parts of poly(glycidyl methacrylate).

Example 5

A melt-kneaded mixture was obtained in the same manner as in Example 1except that 10 parts of dodecenylsuccinic anhydride (manufactured by NewJapan Chemical Co., Ltd., product name “RIKACID DDSA”) was used insteadof 10 parts of poly(glycidyl methacrylate).

Example 6

A melt-kneaded mixture was obtained in the same manner as in Example 1except that 10 parts of hexahydrophthalic anhydride (manufactured by NewJapan Chemical Co., Ltd., product name “RIKACID HH”) was used instead of10 parts of poly(glycidyl methacrylate).

Example 7

A melt-kneaded mixture was obtained in the same manner as in Example 1except that 20 parts of lactide lactate was used instead of 20 parts ofdimethyl sulfone and 5 parts of tetrabromobisphenol A diglycidyl ether(manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., product name“SR-BSP”) was used instead of 10 parts of poly(glycidyl methacrylate).

Example 8

A melt-kneaded mixture was obtained by the same operation carried out asin Example 1 except that 10 parts of poly(glycidyl methacrylate) was notadded.

Example 9

A melt-kneaded mixture was obtained in the same manner as in Example 1except that 10 parts of hydrotalcite (manufactured by Kyowa ChemicalIndustry Co., Ltd., product name “ALCAMIZER (registered trade name) 5”)was used instead of 10 parts of poly(glycidyl methacrylate).

Example 10

A melt-kneaded mixture was obtained in the same manner as in Example 1except that the addition rate of dimethyl sulfone was changed from 20parts to 10 parts and 10 parts of poly(glycidyl methacrylate) was notadded.

Comparative Example 1

Kneading was carried out in the same manner as in Example 1 except thatthe plasticizer and the stabilizer were not added. However, it was notpossible to carry out sufficient kneading and thus no melt-kneadedmixture was obtained. Instead, a resin mass was obtained.

Comparative Example 2

Kneading was carried out in the same manner as in Example 10 except that10 parts of epoxidized soybean oil (manufactured by DIC, product name“W-100-EL”) was used as the plasticizer. However, kneading wascompletely impossible and this a powder aggregate including nomelt-kneaded portion was obtained.

Comparative Example 3

The same operation as in Example 1 was carried out except that 20 partsof dimethyl sulfoxide (also referred to as “DMSO”) was used instead of20 parts of dimethyl sulfone. However, during kneading, foaming occurredand odor was generated. Thus, the melt-kneading operation was not ableto be carried out.

Comparative Example 4

The same operation as in Example 1 was carried out except that 20 partsof N,N-dimethylformamide (also referred to as “DMAc”) was used insteadof 20 parts of dimethyl sulfone. However, during kneading, foamingoccurred and odor was generated. Thus, the melt-kneading operation wasnot able to be carried out.

Comparative Example 5

The same operation as in Example 1 was carried out except that 20 partsof N,N-dimethylacetamide (also referred to as “DMAc”) was used insteadof 20 parts of dimethyl supine. However, during kneading, foamingoccurred and odor was generated. Thus, the melt-kneading operation wasnot able to be carried out.

Hot-pressed samples obtained by preparing the kneaded mixtures ofExamples 1 to 10 and Comparative Examples 1 to 5 as follows were used toevaluate the melt processability thereof. The results are indicated inTable 2 below. Table 2 also indicates the mixing ratio of thethermoplastic modacrylic resin composition.

<Preparation of Hot-Pressed Samples>

Each melt-kneaded mixture or resin mass obtained after kneading was cutout to about 5 g. An aluminum block (80×60×40 mm), an aluminum plate(80×60×1 mm), a spacer aluminum plate (a U shape, 1 mm thick), and analuminum plate (80×60×1 mm) were placed on the lower heater of a HandHot Press Digital HHP-2D (AS ONE) sequentially from the bottom and thenwere preheated for 30 minutes under the condition of 160° C. while beingpressed down by the upper heater. After that, a cut-out melt-kneadedmixture or resin mass was placed under the uppermost aluminum plate(80×60×1 mm), and the aluminum plate (80×60×1 mm) was placed thereabove,which then was hand-pressed for 60 seconds. Thereafter, the aluminumplate (80×60×1 mm), the spacer aluminum plate (a U shape, 1 mm thick),and the aluminum plate (80×60×1 mm) were removed together and then wereplaced between stainless steel (SUS) plates (300×300×1 mm) by the upperand lower sides thereof and a weight of 2 kg was placed on the upper SUSplate, which then was cooled for 10 minutes. After the coolingoperation, the aluminum jig was removed and thus a resin plate with athickness of 1 mm was obtained.

<Melt Processability>

Based on the results of transmitted light observation of the hot-pressedsamples (resin plates) obtained above using an optical microscope (BX51,manufactured by Olympus Corporation, 10× ocular lens, 20× objectivelens, 200× in total), the melt processability was evaluated on thefollowing criteria.

Good: Only less than 100 spots of powder with a particle size of atleast 10 μm exist in a total of 10 visual field observations at ×200magnification.

Poor: At least 100 spots of powder with a particle size of at least 10μm exist in a total of 10 visual field observations at ×200magnification.

Fail: Kneading is not able to be carried out and therefore thehot-pressed sample to be used for observation is not able to be preparedsuitably.

TABLE 2 Modacrylic Other Melt- Resin Additives Plasticizer StabilizerKnead (Parts) (Parts) Type Parts Type Parts ability Ex. 1 100 3.7Dimethyl sulfone 20 Poly(glycidyl 10 Good methacrylate) Ex. 2 100 3.7Dimethyl sulfone 20 Hydrotalcite 10 Good Ex. 3 100 3.7 Dimethyl sulfone20 Hydrotalcite 10 Good Ex. 4 100 3.7 Dimethyl sulfone 20Tetrabromobisphenol 10 Good A diglycidylether Ex. 5 100 3.7 Dimethylsulfone 20 Dodecenylsuccinic 10 Good anhydride Ex. 6 100 3.7 Dimethylsulfone 20 Hexahydrophthalic 10 Good anhydride Ex. 7 100 3.7 Lactidelactate 20 Tetrabromobisphenol  5 Good A diglycidylether Ex. 8 100 3.7Dimethyl sulfone 20 — — Good Ex. 9 100 3.7 Dimethyl sulfone 20Hydrotalcite 10 Good Ex. 10 100 3.7 Dimethyl sulfone 10 — — Good C. Ex.1 100 3.7 — — — — Poor C. Ex. 2 100 3.7 Epoxidized soybean oil 10 — —Poor C. Ex. 3 100 3.7 Dimethyl sulfoxide 20 Poly(glycidyl 10 Failmethacrylate) C. Ex. 4 100 3.7 N,N-Dimethylformamide 20 Poly(glycidyl 10Fail methaciylate) C. Ex. 5 100 3.7 N,N-Dimethylacetamide 20Poly(glycidyl 10 Fail methacrylate)

As can be seen from the results indicated in Table 2 above, thethermoplastic modacrylic resin compositions of Examples 1 to 10, inwhich an organic compound that was compatible with the modacrylic resinand had a boiling point of at least 200° C. was used as the plasticizer,had good melt processability.

On the other hand, the thermoplastic modacrylic resin compositions ofComparative Example 1, in which no plasticizer was contained, andComparative Example 2, in which an epoxidized soybean oil was used asthe plasticizer, had poor melt kneadability and no melt-kneaded mixturewas able to be obtained. Furthermore, in Comparative Examples 3 to 5, inwhich DMSO, DMF, and DMAc that are compatible with the modacrylic resinbut have a boiling point of lower than 200° C. were used as theplasticizer, during kneading, foaming occurred and odor was generated,and thus, the melt-kneading operation was not able to be carried out.

Using hot-pressed samples (resin plates) prepared as described aboveusing the melt-kneaded mixtures of Examples 1 to 7, 9, and 10 as well asthe kneaded resin mass of Comparative Example 1, the degree ofcoloration and transmittance were evaluated as described below. Theresults are indicated in Table 3 below.

<Colorimetric Test>

The lightness L*, chromaticity a*, chromaticity b* in the L*a*b* colorsystem were measured with a spectrophotometer “CM-2600d” (manufacturedby KONICA MINOLTA) using a mask with a diameter of 3 mm and thereby thedegree of coloration of each hot-pressed sample (1-mm thick resin plate)was evaluated. Immediately before the sample measurement, the device wascalibrated with a barium sulfate standard white plate. The L valueindicates the degree of lightness. The a* value indicates that thesample exhibits coloration in green in the case of a minus value oflower than 0 and in red in the case of a plus value higher than 0, andthe higher the absolute value, the more intense the color. The b* valueindicates that the sample exhibits coloration in blue in the case of aminus value of lower than 0 and in yellow in the case of a plus valuehigher than 0, and the higher the absolute value, the more intense thecolor. With a copy paper (a PPC paper) being placed underneath,measurement was carried out five times with respect to each hot-pressedsample while the measurement point was changed, and the average valuesthereof were calculated. As a blank, similarly, using a copy paper (aPPC paper), measurement was carried out five times while the measurementpoint was changed, and the average values thereof were calculated. Fromthe average value of the resultant L value, a* value, and h* value, thecolor difference ΔE*ab from the blank in the L*a*b* space wascalculated. The calculated values are indicated in Table 3. The range ofΔE*ab was divided into four stages of criteria as follows, which wereused as judgment bases for the overall judgment. A higher criteria valuemeans a higher coloration suppressing effect.

4: ΔE*ab is 0 to 25.

3: ΔE*ab is higher than 25 but not higher than 50.

2: ΔE*ab is higher than 50 but not higher than 75.

1: ΔE*ab is higher than 75 but not higher than 100.

<Measurement of Transmittance>

The transmittance of each hot-pressed sample (1-mm thick resin plate)was measured using transmittance measurement software U6039-01(manufactured by Hamamatsu Photonics), with a MULTI CHANNEL ANALYZERPMA-11 (manufactured by Hamamatsu Photonics) being connected to anoptical microscope (manufactured by Olympus, “BX51”). 10× objective lenswas used. The transmittance was measured at two points, 476.59 nm and625.31 m. The light amount was adjusted so that the transmittance ofoptical glass was 4630±50 at 476.59 nm and 16100±100 at 625.31 nm. Thetransmittance was measured ten times while the measurement point waschanged, and the average value was calculated. The average valuesobtained at respective wavelengths were further averaged. Thetransmittance can be represented by Formula 1, where T is atransmittance, α is an absorption coefficient, and x is a light pathlength.[Mathematical Formula 1]T=e ^(−αx)  (1)

In Formula (1) above, e is the base of natural logarithm, Napier'sconstant. With respect to each hot-pressed plate sample, the absorptioncoefficient α was calculated as a value per cm of light path length.Table 3 indicates the calculated values. The range of the absorptioncoefficients α was divided into the following four stages of criteria,which were used as judgment bases for the overall judgment. A highercriteria value means better transparency.

4: The absorption coefficient α is 0 to 10.

3: The absorption coefficient α is higher than 10 but not higher than20.

2: The absorption coefficient α is higher than 20 hut not higher than30.

1: The absorption coefficient α is higher than 30.

<Overall Judgment>

The total value obtained by adding up the values of judgment criteriaevaluated by the colorimetric test and the transmittance measurement wasused for the overall judgment. When the criteria value of each of thecolorimetric test and the transmittance is at least 2 and the totalvalue is at least 4, it was judged as good, while when the total valueof the colorimetric test and the transmittance is 3 or lower, it wasjudged as fail. The higher the total value, the better the colorationsuppression, and the better the transparency.

TABLE 3 Colorimetry a* b* Transmittance Green in Blue in Absorption L*Minus, Red Minus, Yellow Coefficience Overall Lightness in Plus in PlusΔE*ab Judgment λ₁ λ₂ Average (per 1 cm) Judgment Judgment Ex. 1 83.0−1.85 40.33 41 3 49% 49% 49% 7.1 4 7 Ex. 2 71.2 −0.21 37.80 45 3 26% 31%29% 12.5 3 6 Ex. 3 75.7 −0.91 37.76 42 3 32% 41% 36% 10.1 3 6 Ex. 4 75.30.12 42.76 47 3 28% 41% 34% 10.8 3 6 Ex. 5 69.8 3.05 47.24 53 2 21% 32%27% 13.2 3 5 Ex. 6 73.2 1.86 47.60 52 2 28% 40% 34% 10.7 3 5 Ex. 7 67.82.86 50.14 57 2 25% 42% 34% 10.8 3 5 Ex. 9 77.8 1.33 37.38 41 3  9%  5% 7% 26.6 2 5 Ex. 10 44.1 11.06 27.44 60 2  8% 18% 13% 20.3 2 4 C. Ex. 155.0 6.78 31.73 52 2  7%  2%  5% 30.8 1 3 Blank 97.3 −0.04 1.74 0 4100%  100%  100%  0.0 4 — λ₁ = 476.59 nm and λ₂ = 625.31 nm

From the results indicated in Table 3 above, it was found thatcontaining a stabilizer for modacrylic resin suppressed colorationand/or improved transparency. Particularly, the use of an epoxy-basedheat stabilizer or a hydrotalcite-based heat stabilizer tended to resultin better effects.

Example 11

<Production of Molten Material of Modacrylic Resin Composition>

To 100 pans by weight of the modacrylic resin powder obtained inSynthesis Example 1, 20 parts by weight of dimethyl sulfone as aplasticizer, 7.5 parts by weight of tetrabromobisphenol A diglycidylether (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., product name“SR-BSP”) and 2.5 parts by weight of hydrotalcite (manufactured by KyowaChemical Industry Co., Ltd., product name “ALCAMIZER (registered tradename) 1”) as stabilizers, as well as 0.5 part by weight of(meth)acrylate-based polymer (manufactured by Kaneka Corporation,product name “Kane Ace PA20”), 0.5 part by weight of calcium stearate,1.2 parts by weight of magnesium stearate, 0.8 part by weight ofsynthetic polyethylene wax, and 0.7 part by weight of stearic acid(manufactured by NOF Corporation, product name “Stearic Acid Sakura”) asother additives were added, which then was increased in temperature to110° C. while being mixed together using a Henschel mixer. Thereafter,it was cooled down to 50° C., and thereby a powder mixture was obtained.Subsequently, the powder mixture was extruded with the labo extruder(manufactured by Toyo Seiki Seisaku-sho, Ltd., model number “4C150”, acombination of a 20-mm extrusion unit and a 2-mm strand nozzle), andthus a strand was obtained. The extruder was operated in the temperaturerange of 120 to 175° C. The resultant strand was air-cooled and then waspelletized.

<Spinning Process>

The resultant pellets were melt-extruded with the labo extruder(manufactured by Toyo Seiki Seisaku-sho. Ltd., model number “4C150”, acombination of a 20-mm extrusion unit, a downward die for melt viscositymeasurement, and a spinning nozzle with a diameter of 0.4 mm) under theconditions of an extruder temperature of 120 to 220° C., a nozzletemperature of 195° C., a heating cylinder (45 mm×50 mm) temperature of400° C., and a linear velocity of a discharged material of 7.5 to 8.3m/min. This was taken off at 80 m/min while being allowed to contactwith a cooling tube, inside of which water flows, and thus undrawn yarnswith a fineness of approximately 108 dtex were obtained. The resultantundrawn yarns were thy-heat drawn in a dry heat atmosphere of 105° C. ata draw ratio of 1.8 times and thereby acrylic fibers with a single fiberfineness of approximately 60 dtex were obtained.

Example 12

<Production of Molten Material of Modacrylic Resin Composition>

To 100 parts by weight of the modacrylic resin powder obtained inSynthesis Example 1, 25 parts by weight of dimethyl sulfone as aplasticizer, 2.5 parts by weight of hydrotalcite (manufactured by KyowaChemical Industry Co., Ltd., product name “ALCAMIZER (registered tradename) 1”) as a stabilizer, as well as 0.2 part by weight of(meth)acrylate-based polymer (manufactured by Kaneka Corporation,product name “Kane Ace PA20”), 6 parts by weight of (meth)acrylate-basedpolymer (manufactured by Kaneka Corporation, product name “Kane AcePA101”), 0.2 part by weight of calcium stearate, 0.3 part by weight ofmagnesium stearate, 0.2 part by weight of synthetic polyethylene wax,and 0.18 part by weight of stearic acid (manufactured by NOFCorporation, product name “Stearic Acid Sakura”) as other additives wereadded, which then was increased in temperature to 110° C. while beingmixed together using a Henschel mixer. Thereafter, it was cooled down to50° C., and thereby a powder mixture was obtained. Subsequently, thepowder mixture was extruded with the labo extruder (manufactured by ToyoSeiki Seisaku-sho. Ltd., model number “4C150”, a combination of a 20-mmextrusion unit and a 2-mm strand nozzle), and thus a strand wasobtained. The extruder was operated in the temperature range of 125 to165° C. The resultant strand was air-cooled and then was pelletized.

<Spinning Process>

The resultant pellets were melt-extruded with the labo extruder(Manufactured by Toyo Seiki Seisaku-sho, Ltd., model number “4C150”, acombination of a 20-mm extrusion unit, a downward die for melt viscositymeasurement, and a spinning nozzle with a diameter of 4 mm) under theconditions of an extruder temperature of 120 to 220° C., a nozzletemperature of 31.4° C., and a linear velocity of a discharged materialof 7.4 to 8.5 m/min. This was taken off at 60 m/min while being allowedto contact with a cooling tube, inside of which water flows, and thusundrawn yarns with a fineness of approximately 167 dtex were obtained. Adrive roll was placed both before and after a hot water bath with anadjusted temperature of 95° C., with the drive roll being set to have anentry speed of 0.5 m/min and an exit speed of 1.0 m/min, and the undrawnyarns obtained in the spinning process were drawn in the hot water for aretention time of approximately 40 seconds. Thereafter, the fibers drawnin the hot water fixed at a length of 20 cm were placed into an oven setat 115° C. and this was maintained for two minutes. After that, theywere drawn to the length 1.1 times longer than the original length andthen were taken out from the oven to be air-cooled. Thus drawn yarnswith a fineness of 76 dTex were obtained.

TABLE 4 Standard Test Knot Test Elongation Young's Elongation FinenessStrength Rate Modulus Fineness Strength Rate (dTex) (cN/dTex) (%) (Gpa)(dTex) (cN/dTex) (%) Ex. 11 60.3 0.95 19.1 4.9 60.6 0.75 17.9 Ex. 1276.1 1.33 24.6 3.8 76.0 1.12 21.5

From the results of Examples 11 and 12 described above, in thethermoplastic modacrylic resin composition containing the modacrylicresin and the plasticizer, the use of the organic compound that iscompatible with the modacrylic resin and has a boiling point of at least200° C. as the plasticizer made it possible to melt-spin thethermoplastic modacrylic resin composition and thereby to obtain acrylicfibers. The cross-sections of the acrylic fibers obtained in Example 11and 12 were observed with a laser microscope (manufactured by KEYENCE,ultra-deep color 3D profile measurement microscope “VK-9500”). Thecross-sectional photograph (×1000) of the acrylic fibers of Example 12is shown in the FIGURE. In the FIGURE, a flat cross-section object is adummy fiber for filling used in the laser microscope observation. As canbe seen from the FIGURE, the cross-sections of the acrylic fibersobtained by melt-spinning had no difference between the outer layerportion and the core part of the central portion of the fibers and wereuniform and dense.

Although the disclosure has been described with respect to only alimited number of embodiments, those skilled in the art, having benefitof this disclosure, will appreciate that various other embodiments maybe devised without departing from the scope of the present invention.Accordingly, the scope of the present invention should be limited onlyby the attached claims.

What is claimed is:
 1. Acrylic fibers composed of a thermoplasticmodacrylic resin composition, wherein the thermoplastic modacrylic resincomposition comprises a modacrylic resin, a plasticizer, and astabilizer, wherein the thermoplastic modacrylic resin compositioncomprises 5 to 50 parts by weight of the plasticizer with respect to 100parts by weight of the modacrylic resin, wherein the stabilizer isselected from the group consisting of an epoxy-based heat stabilizer, ahydrotalcite-based heat stabilizer, an aliphatic acid anhydride, and analicyclic acid anhydride, wherein the modacrylic resin comprises 15 to85 wt % of acrylonitrile, 15 to 85 wt % of vinyl chloride and/orvinylidene chloride, and 0 to 20 wt % of another vinyl monomer, whereinthe plasticizer is an organic compound that is compatible with themodacrylic resin and has a boiling point of at least 200° C., andwherein the acrylic fibers have a predetermined shape and a single fiberfineness of 60.3 to 100 dtex.
 2. The acrylic fibers according to claim1, wherein the plasticizer is at least one selected from the groupconsisting of: dimethyl sulfone, diethyl sulfone, dipropyl sulfone,dibutyl sulfone, diphenyl sulfone, vinyl sulfone, ethyl methyl sulfone,methyl phenyl sulfone, methyl vinyl sulfone, 3-methylsulfolane, dipropylsulfoxide, tetramethylene sulfoxide, diisopropyl sulfoxide, methylphenyl sulfoxide, dibutyl sulfoxide, diisobutyl sulfoxide, di-p-tolylsulfoxide, diphenyl sulfoxide, benzyl sulfoxide, lactide, pyrrolidone,ε-caprolactam, N-methylcaprolactam, γ-butyrolactone, γ-hexalactone,γ-heptalactone, γ-octalactone, ε-caprolactone, and ε-octalactone.
 3. Theacrylic fibers according to claim 1, wherein the thermoplasticmodacrylic resin composition comprises 0.1 to 30 parts by weight of thestabilizer with respect to 100 parts by weight of the modacrylic resin.4. The acrylic fibers according to claim 1, wherein the plasticizer hasa melting point of at least 60° C.
 5. The acrylic fibers according toclaim 1, wherein the plasticizer is at least one selected from the groupconsisting of dimethyl sulfone and lactide.
 6. The acrylic fibersaccording to claim 1, wherein the stabilizer is at least one selectedfrom the group consisting of poly(glycidyl methacrylate),tetrabromobisphenol A diglycidyl ether, hydrotalcite, adodecenylsuccinic anhydride, and a hexahydrophthalic anhydride.